Effect of potassium precursors on the thermal stability of K-promoted Ru/carbon catalysts for ammonia synthesis

Abstract

The effect of K precursors on the stability of K-promoted Ru/carbon catalysts for ammonia synthesis was studied.

Role of surface defects of carbon nanotubes on catalytic performance of barium promoted ruthenium catalyst for ammonia synthesis

“…This observation can be explained by an easier methanation of the Ru/CNTs-D samples than for other two samples owing to the strong interaction between Ru NPs and the carbon support [36] . The last peaks of Ru/CNTs, Ru/CNTs-O and Ru/CNTs-D samples are higher than 470 °C, which can be considered as the decomposition of oxygen-containing groups on the surface of the samples [39] ; both water, CO and CO 2 molecules are detected by a mass spectrometer in this temperature range. See supporting information Fig.…”

“…Since the treatment of the catalysts under severe condition is helpful for estimating the stability of carbon-supported Ru catalysts, a high temperature treatment process at 475 °C for 14 h was carried out. Most of unstable catalysts resulted in a decreasing performance after the severer thermal treatments [39,40] . To evaluate the stability of the catalysts, Fig.…”

Recent Advances in Heterogeneous Catalysis for Ammonia Synthesis

“…Initial studies have shown Ba and K promoters with oxygen rich functional groups present on AC has improved Ru dispersion, stability and catalytic activity in NH 3 synthesis. [149][150][151] Recently Jiang et al have reported that addition of La to BaÀ KÀ Ru/AC has inhibited methanation of carbon. [152] The strong interaction of reduced LaOx layer beneath Ru particles has suppressed contact between carbon support and Ru particles as result inhibited formation of H species necessary for methanation.…”

“…However, this was overcome by doping, functionalization of carbon support along with addition of alkali/alkaline metal as promoter. Initial studies have shown Ba and K promoters with oxygen rich functional groups present on AC has improved Ru dispersion, stability and catalytic activity in NH 3 synthesis [149–151] . Recently Jiang et al.…”

A highly stable and active mesoporous ruthenium catalyst for ammonia synthesis prepared by a RuCl3/SiO2-templated approach

“…It is generally accepted that both Ba and K are necessary for ammonia synthesis, as K acts as an electron donor [21,29] and Ba electrostatically modifies the potential around the B5 sites (electronic promotion), rendering them significantly more active for N2 dissociation [23]. Therefore, Ru-MC and Ru/MC were impregnated with Ba(NO3)2 and KNO3 as promoters.…”